Nonvolatile memory retains stored data when power is removed, which is required or at least highly desirable in many different types of computers and countless other electronic devices. Nonvolatile memory devices have therefore always been one of the more predominant devices fabricated in semiconductor manufacturing facilities.
Various types of nonvolatile memory (NVM) technologies exist. Most nonvolatile memory devices such as programmable read-only memory (PROM), electrically programmable read-only-memory (EPROM), electrically erasable programmable ROM (EEPROM) flash EEPROM's or other electric memory devices require additional processing operations which increases costs, increases the likelihood of misprocessing and requires a longer manufacturing time. Additionally, there are various types of one-time programmable (OTP) memory technologies in the market today that represent embedded nonvolatile memory (NVM) technologies. The main OTP memory technologies include mask ROM, floating gate, electrical fuse and anti-fuse. Anti-fuse devices have been in the market for several decades in the semiconductor industry for one-time programmable devices and typically use separately created metal/insulator/metal (MIM) structures or polysilicon/dielectric/diffusion area structures. Additional, dedicated process steps are required to create these nonvolatile memory elements. As has always been the case in semiconductor device manufacturing, there is also an ongoing drive to produce smaller, more highly integrated devices that require less space and this applies to all device structures including NVM cells.
It would therefore be desirable to create a compact NVM cell that utilizes the processing operations used to produce other semiconductor structures and which does not require separate dedicated processing operations simply to form the NVM.